The long term goal of this work is to discover how protein synthesis, a metabolic pathway essential to cell growth, is controlled by polypeptide growth factor-receptor interactions, by nutrients, and by physical stresses. This laboratory has recently found that regulation of phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF-2) is an important mechanism controlling the rate of polypeptide chain initiation in Ehrlich ascites tumor cells deprived of serum growth factors, or of an essential amino acid, and in cells stressed by heat shock. It has also been shown that the kinase which phosphorylates eIF-2 alpha in the Ehrlich cell is different from the two known eIF-2 alpha kinases. The kinase will be purified from the Ehrlich cell and characterized, in order that the regulation of its activity can be elucidated. This laboratory has also recently found that reduction in cellular calcium concentration and inhibition of calmodulin function cause a large inhibition of the protein synthesis rate in Ehrlich cells. A factor has been recognized in the ribosomal KCl wash fraction of Ehrlich cells and rabbit reticulocytes which counteracts these inhibitions. It is proposed to purify and characterize this factor. Characterization of the factor will indicate whether there is a mechanism regulating protein synthesis which is based upon calmodulin.